The aim of this research is to assess the recent changes in hospital nursing staff and their impact on the quality of patient care. Whether nursing staff levels and mix have declined, and if so, whether this has negatively impacted on the quality of patient care is a concern of practitioners and patients alike. Prior research has been controversial and inconclusive. This study assesses: 1 ) the recent changes in hospital nursing staff; 2) the structural relationship between nurse staffing and the quality of patient care; 3) the structural relationship between other hospital characteristics and restructuring actions on the one hand, and the quality of patient care on the other hand; and 4) the impact of the recent nursing staff changes on the quality of patient care. Research hypotheses are that from 1992-1996: a) the ratios of all categories of nursing personnel to patient load, of licensed to unlicensed nursing personnel, and of full to part time nursing personnel have declined; b) higher levels and mix of nursing staff are associated with lower patient mortality, readmission, and nosocomial infection rates; c) hospital restructuring overall is associated with higher mortality, readmission, and nosocomial infection rates; and d) the reductions in the level and mix of nursing staff from 1992-1996 described above are associated with increases in patient mortality, readmission, and nosocomial infection rates. A panel data set from patient and hospital records in all Pennsylvania hospitals is utilized in a descriptive model and a fixed or random effects linear regression model to test the hypotheses.